CVE-2026-40110
Jupyter Server is the backend for Jupyter web applications. In versions 2.17.0 and earlier, the Origin header validation uses Python's re.match() to check incoming origins against the allow_origin_pat configuration value. Because re.match() only anchors at the start of the string and does not require a full match, a pattern intended to match only a trusted domain (e.g., trusted.example.com) will also match any origin that begins with that domain followed by additional characters (e.g., trusted.example.com.evil.com). An attacker who controls such a domain can bypass the CORS origin restriction and make cross-origin requests to the Jupyter Server API from an untrusted site. This issue has been fixed in version 2.18.0.
Scoring
- Severity
- HIGH
- CVSS base score
- 7.6
- CVSS vector
- CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:L/SC:L/SI:L/SA:L
- EPSS probability
- 0.34%
- CWE
- CWE-777
- Published
- 2026-05-05
- Last modified
- 2026-07-22
Affected products
- jupyter-server jupyter_server
Weakness type
Related vulnerabilities
- CVE-2026-22068 — Apache Traffic Server: Regex mappings match with malicious domain names
- CVE-2026-56021 — Webmin information disclosure via regex pattern
- CVE-2026-39087 — ntfy before 2.22.0 allows SSRF because of an unanchored regular expression.